The present invention relates to an ink jet recording apparatus and, in particular, to a technique for reducing ink discharged at the time of maintenance of nozzles.
In the prior art, ink jet recording apparatuses have been realized that can perform color recording by using ink of a plurality of colors (e.g., yellow (“Y”, hereafter), cyan (“C”, hereafter), magenta (“M”, hereafter), red (“R”, hereafter), green (“G”, hereafter), blue (“B”, hereafter), photo black (“photo-K”, hereafter), and black (“K”, hereafter)). In such an ink jet recording apparatus, nozzles for discharging each color ink are provided in a recording head. Then, ink is selectively discharged from each nozzle onto a recording medium, so that an image is recorded onto the recording medium.
Meanwhile, it is known that when dust or air enters into the nozzles or alternatively when ink in the nozzles dries up and solidifies, the nozzles are clogged and go into a state that ink cannot be discharged (that is, non-discharge state). In order that this non-discharge state should be recovered into a normal state, various kinds of maintenance operations are performed like a suction purging operation, a positive pressure purging operation, and a flushing operation. At the time of execution of such maintenance operations, new ink is also discharged forcedly in order that the dust, the air, or the solidified ink should forcedly be removed from the inside of the nozzles. The ink discharged at the time is eventually discarded when stored into a waste ink reservoir or alternatively absorbed by a waste ink absorbing material as described in Japanese Patent Application Laid-Open No. H4-364960 (1992) (page 4) and Japanese Patent Application Laid-Open No. H8-132640 (1996) (page 6).
Here, the situation that a large amount of ink not used in recording is discarded at the time of maintenance operations described above indicates that the amount of ink decreases that could be used for recording. This has caused the problem of an increase in the running cost such as the ink cost.
Further, in the case that the above-mentioned recording head that performs color recording is constructed so as to perform the maintenance operations for each of different inks independently, there arises a problem that the size of the apparatus is increased and that the control thereof is complicated.
Thus, in order to simplify the configuration and control of the maintenance mechanism, the maintenance mechanism has been invented in which the maintenance operation is performed simultaneously for a plurality of recording heads by sharing one maintenance mechanism with a plurality of recording heads, and by employing a nozzle cap capable of covering the plurality of recording heads.